• Combined measurement of IgG & Complement to over 90 foods from a single blood serum sample
    (Assists confirmation of inflammatory response to IgG positive foods)
  • The only test on the market that measures both IgG and immune complexes containing the complement fragment ‘C3d’ to multiple food antigens.

IgG (Immunoglobulin G, total)

IgG are antibodies that provide long-term resistance to infections and have a much longer half-life than the traditional IgE allergy. The IgG antibody response creates sensitivity to a particular food. Symptoms may be less severe than with IgE allergic reaction and can manifest anywhere from 3-72 hours after exposure. The delayed response makes sensitivities difficult to identify without a test.

IgG reactions create inflammation that makes many pathologies worse. Sensitivity symptoms range from headache and nausea to seizure and hyperactivity, or simply just fatigue, bloating, mood changes, or dark circles under the eyes. Sensitivities can improve with treatment and improved gut health.

C3d (Complement component 3)

The Dietary Antigen Test (IgG with Complement) measures Complement activation for multiple foods. Complement activation is well-defined in the research as not only a cause of inflammation but one of the strongest causes.

C3d is an activator of the Complement cascade system. Reaction to the specified food will worsen if C3d activation is present along with an IgG antibody response.

When C3d is activated in response to an antigen, the C3 portion attaches to the antigen. This activation, even though it is independent, will amplify the reaction that occurs with total IgG greatly increasing inflammation and symptoms of sensitivity.

What is the C3d Pathway?

The Complement pathway acts as the body’s SWAT team to aggressively attack and clear threats, such as bacteria, viruses, protozoa, and allergens. It is part of the innate immune system, meaning that we are born with this immune defense mechanism.

Complement components patrol the blood harmlessly, but in an instant can go on the attack to kill and remove dangerous molecules from the body. When activated, the Complement pathway sets off a domino effect of inflammatory cytokines, mast cell degranulation (Histamine), and cell membrane destruction. It is a powerful protective force but can damage tissues if not kept under control.

Complement is a quantifiable, reliable biomarker of tissue inflammation.

What is the Relationship Between C3d Activation and IgG Reactivity?

It’s important to note that IgG is not the only factor in the reaction level for food sensitivities. To get a more complete look at the patient’s response and reaction level to that specific food, we often also need to measure the patient’s C3d reaction to that same food.

Complement serves as a link between the innate and adaptive immune response. This is because Complement uses immunoglobulins to help identify dangerous molecules that should be destroyed. IgG1, IgG3, and IgM antibodies can all activate Complement.

Why C3d Activation is so Important in Food Sensitivity Testing

  • When activated, the C3 component of the Complement system attaches to potential food antigens; these antigens may also induce a response from the acquired immune system.
  • Measurement of Complement can increase the inflammatory potential of a reaction to food by 1000 to 10,000 fold.
  • Complement helps differentiate which IgG titer is more inflammatory than others.
  • Complement is the link between the innate immune system and an acquired immune response, differentiating which white blood cell activations are truly inflammatory, limiting false positives.


Vickery BP, Scurlock AM, Jones SM, Burks AW. Mechanisms of immune tolerance relevant to food allergy. J Allergy Clin Immunol. 2011;127(3):576.

Chehade M, Mayer L. Oral tolerance and its relation to food hypersensitivities. J Allergy Clin Immunol. 2005;115(1):3.

Burks AW, Laubach S, Jones SM. Oral tolerance, food allergy, and immunotherapy: implications for future treatment. J Allergy Clin Immunol. 2008;121(6):1344.